Marion Jones tests positive for EPO

Marion Jones, the triple Olympics champion in 2000, who has been dogged by stories concerning drugs in recent years, was last night facing the biggest personal crisis of her life after a positive test for erythropoietin taken at the US championships in Indianapolis in June.

The American sprinter was due to compete at last night's Golden League meeting in Zurich but left the hotel where the athletes were staying at 6am, reportedly "for personal reasons". Many experts had been surprised by the resurgence of form of Jones, now 30, who had run the 100m in 10.91sec in Rome in July.

Erythropoietin (EPO) has been more commonly associated with cyclists and the Tour de France in particular. If the B sample confirms the A sample as revealed in the test conducted by the International Association of Athletics Federations, Jones faces a two-year ban from athletics.

In 1999 Jones's then husband, the world shot-put champion CJ Hunter, tested positive for record levels of the anabolic steroid nandralone which forced him to withdraw from the 2000 Olympics in Sydney, where she won both sprints and a third gold in the 4x400m relay as well as bronze medals in the short relay and long jump.

After he was banned for two years Jones left him and started a relationship with Tim Montgomery, who like her was coached by the Jamaican-born Trevor Graham. Montgomery set a world record for the 100m of 9.78 sec at Paris in 2002, a mark subsequently annulled after he was banned for two years in December due to evidence given in a federal investigation into the Bay Area Laboratory Cooperative (Balco) in San Francisco.

A number of witnesses involved in the case claimed Jones, a former basketball player, was involved in taking banned performance-enhancing drugs. She has always denied the allegation.

Graham has been linked with 10 athletes to have failed drugs tests. That could rise to 11 if Justin Gatlin, the world and Olympic 100m champion, is found guilty of taking the anabolic steroid testosterone, for which he has tested positive.

Charlie Wells, Jones's agent, had his mobile phone switched off last night and was unavailable for comment.